Pump

ABSTRACT

A pump and drive motor combination in which a pump impeller is mounted on one end of the motor rotor and a common housing is provided enclosing the motor and impeller. A sealing sleeve in the housing seals between the stator and the rotor-impeller structure while fluid inlet and outlet ports in opposite ends of the housing communicate with opposite ends of the sleeve. A hollow shaft carried by the housing at the inlet end extends into the rotor and rotatably supports the rotor while conveying fluid from the fluid inlet port of the housing to the inlet side of the impeller. The outlet side of the impeller communicates with the fluid outlet port of the housing.

United States Patent Dannenmann et a1,

[ PUMP [75] Inventors: Paul Dannenmann, Welzheim;

Gunter Kratz, Plochingen, both of Germany [73] Assignee: G. Bauknecht Gesellschaft mit beschrankter Hattung Electrotechnische Fabrilten, Stuttgart, Germany [22] Filed: May 17, 1973 [21] App]. No.: 361,048

[30] Foreign Application Priority Data May 18, 1972 Germany 2224213 May 8, 1973 Germany 2323089 1 [52] U.S. Cl. 417/356 [51] Int. Cl. F04b 17/00 [58] Field of Search 417/356 [56] References Cited UNITED STATES PATENTS 2,312,848 3/1943 Pezzillo 417/356 2,485,408 10/1949 Pezzillo 417/356 1 Mar. 11, 1975 2,535,695 12/1950 Pezzillo, Jr 417/356 2,537,310 1/1951 Lapp 417/356 3,164,096 1/1965 Hallerback 417/356 3,719,436 3/1973 McFarlin 417/356 FOREIGN PATENTS OR APPLICATIONS 1,059,329 6/1952 France 417/356 Primary E.\-aminerC. J. Husar Attorney, Agenl, 0r Firm-Walter Becker [57] ABSTRACT A pump and drive motor combination in which a pump impeller is mounted on one end of the motor rotor and a common housing is provided enclosing the motor and impeller. A sealing sleeve in the housing seals between the stator and the rotor-impeller structure while fluid inlet and outlet ports in opposite ends of the housing communicate with opposite ends ofthe sleeve. A hollow shaft carried by the housing at the inlet end extends into the rotor and rotatably supports the rotor while conveying fluid from the fluid inlet port of the housing to the inlet side of the impeller. The outlet side of the impeller communicates with the fluid outlet port of the housing.

17 Claims, 6 Drawing Figures PATENTED 15975 7% 870 438 snmaure PATENTED H9175 870.438

SHEET u I]? 6 PUMP The present invention concerns a pump with a collimator stator sleeve motor pump unit which is coaxially arranged with regard to the pump rotor and has a common housing with the pump. The rotor of the collimator stator sleeve motor pump unit is sealed relative to the stator by means of a collimator which is arranged between the rotor of the stator sleeve motor pump unit and the stator and has its ends resting in the interior of the housing by means of annular flanges. The pump rotor and the rotor of the collimator stator sleeve motor pump unit are mounted on a hollow shaft which is arranged in the housing and which is in communication with the suction opening and the pressure opening of the housing which has a cover at least at one of its end faces.

According to a heretofore known pump of this type, the hollow shaft is designed as a separate structural element and is connected by supporting walls to the collimator which is arranged at a relatively great distance from the mantle of the hollow shaft. The supporting walls are at both sides by means of a housing cover on each end face of the housing fixed with regard to the ends of the collimator and with regard to a central housing part. Experience has shown that with a pump of this type aligning problems occur, particularly with regard to the rotor on the central hollow shaft relative to the collimator, which problems are difficult to master, and the solution of which problems requires an expensive manufacture of the complicated supporting walls and their connecting areas. Furthermore, the assembly and disassembly as well as the servicing of such pumps is rather difficult.

It is, therefore, an object of the present invention to provide a pump of the above described general character which will have a simplified construction and which will permit an economic problem-free mass production, while the pump will be easy to assemble and to disassemble whenever an exchange of parts becomes necessary.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

FIG. 1 illustrates a pump according to the present invention, partly in axial section and partly in view.

FIG. 2 is a top view of the pump of FIG. 1.

FIG. 3 represents an axial section through a modified pump according to the invention.

FIGS. 4-6 respectively illustrate further embodiments of a pump according to the invention in an illustration similar to that of FIG. 3.

The pump according to the present invention is characterized primarily in that the hollow shaft is designed as knock-outspindle which is inserted into a holding flange at an end face of the housing and which by means of at least one collar is resting against a supporting surface of the holding flange and is secured against axial displacement. The pump according to the invention is furthermore characterized in that a first flange of the collimator is located between that end face of the rotor which is adjacent to the holding flange and that end face of the housing which is adjacent thereto and rests against an inner radial abutment surface of the holding flange.

Referring now to the drawings in detail, in which corresponding structural elements have been designated with the same reference numerals in the difference figures, the illustrated pumps substantially comprise a cylindrical housing 1 with two end walls 2 and 3 and a housing mantle 4, one end wall 2 being formed by an axially firmly clamped-in but detachable housing cover. According to the embodiment illustrated in FIGS. 1 and 2, the circumference of the housing cover 2 as well as the circumference of the mantle 4 of housing 1 are each provided with two diametrically oppositely located protruding plates 5, 6. In the plates 5' of the housing cover 2 passages are provided, and in the plates 6 of the housing mantle 4 threaded bores are provided for a clamping screw 7. In the embodiments illustrated in FIGS. 3-6, the circumference of the housing cover 2 as well as the circumference of the oppositely located end wall 3 have distributed thereover at least two passages 5 and 6 each which are passed through by a clamping screw 7. By means of the clamping screws 7 which are axis-parallel to the pump, the housing cover 2 is firmly clamped against the housing mantle 4. In the outer radial region of the housing cover 2, an annular shoulder 8 is located on the inner side of the housing cover 2 which shoulder extends over a corresponding axially protruding annular collar 9 of the housing mantle 4 and centers the same in such a way that the housing cover 2 is precisely aligned with regard to the remaining housing portion.

Arranged in housing 1 and coaxial therewith is a collimator motor 10 the stator 11 of which is connected to the inner circumferential surface of the housing mantle 4 in the central portion of its length. for instance, by a press fit. At both sides of the laminated packet of the stator 11 there are provided the windings or coils 12 of the stator which extend approximately to the respective pertaining end wall of housing 1. That end wall 3 of the housing which is located opposite the housing cover 2 has a holding flange 13'located in the axis of the pump. This flange 13 extends over the major portion of its length into the housing 1, while the flange 13 forms one piece with the end wall 3. In view of the fact that the housing mantle 4, the end wall 3 and the holding flange 13 are formed as one single piece, a stable and simple construction is obtained. The arrangement of the holding flange 13 over a major portion of its length in the interior of the housing 1 permits a construction which saves space in axial direction. Inserted into the bore 14 of the holding flange 13 is a sleeveshaped hollow shaft 15 with a plug section 16 the outer circumferential surface of which engages the bore 14 with press fit and thus is secured against axial displacement. The hollow shaft 15 forms a knock-out spindle and a conveying pipe. According to the embodiment of FIGS. 1-3, the plug section 16 of the hollow shaft 15 merges with a section 17 which is provided with the outer thread and which has only a slightly smaller outer diameter than the section 16 so that the hollow shaft 15 can from the interior of the housing be inserted into the holding flange 13 in such a way that the section 17 with its outer thread protrudes beyond the outer side of the end wall 3 and the holding flange 13. At that end of the plug section 16 of shaft 15 which faces away from the section 17 provided with an outer thread, it is possible, as shown in FIG. 1, to provide an annular grooveshaped cut 18 on the outer circumference of the hollow shaft 15. The outer diameter of the cut 18 is only slightly smaller than the outer diameter of the plug section 16. The cut 18 is adjacent an annular collar 19 which protrudes beyond the outer diameter of the ho]- low shaft 15 and forms a single piece therewith. As a result thereof, a stable construction is obtained. According to the embodiment of FIGS. 1 and 2, the outer diameter of the annular collar 19 equals approximately the outer diameter of the holding flange l3 and thus furnishes a particularly large supporting surface.

On that side of the annular disc-shaped inner collar 19 which faces away from the plug section 16, the hollow shaft 15 forms a bearing section 20 which freely extends into the interior of the housing 1 and the outer diameter of which is only slightly less than the outer diameter of the plug section 16 or, as is the case with the embodiment of FIG. 6, equals the outer diameter of the plug section 16. Rotatably journalled on the bearing section 20 is a bearing bushing 21 which extends approximately over the entire length of the bearing section 20. This bearing bushing 21 is pressed into the rotor 22 of the collimator motor which rotor 22 may be formed, for instance, by lamellae or in a laminated manner. That end face of rotor 22 which faces away from the plug section 16 is located approximately in the plane of the inner end face of the hollow shaft 15, which inner end face is formed by the free end of the bearing section 20. Connected to this end face of rotor 22 is a spacer and connecting ring 23 which in axial section is angle-shaped and which extends into the inner bore of the rotor 2. Ring 23 may extend, for instance, to the corresponding end face of the bearing bushing 21 (see FIG. 1) or may rest against the adjacent end face of the bearing bushing 21 and may be fixed relative to the rotor (FIGS. 3-6) by means of slotted or splined pins 47 or the like. Connected to the outer end face of the ring 23 is a pump rotor 24 which is axially aligned with the rotor 22 and which is located between the inner end of the hollow shaft and the housing cover 2. Connected to that end face of the pump rotor 24 which faces away from the inner end of the hollow shaft 15 is a disc-shaped pump wall 25 which may form a single piece with the rotor blades 26 extending from the rotor shaft and the connecting ring 23. Located opposite to the pump wheel wall 25 is a counter surface 27 which is composed of annular segment-shaped surface sections and is formed by corresponding ribs 28 which form one piece with the housing cover 2 and protrude inwardly beyond the inner side of the housing cover 2. In this way, the rotor 22 and the pump rotor 24 are between the inner collar 19 of hollow shaft 15 and the counter surface 27 secured with a predetermined axial play against too great an axial displacement when the pump rotor 24 is due to occurring forces pulled away from the collar 19.

According to the embodiments of FIGS. 3-6, the pump wheel wall 25 has its outer side provided with a truncated cone-shaped extension 48 which cooperates with a counter surface 49 of a deblocking device 50 which counter surface 49 is rotatable from the outside. When actuating the deblocking device 50 by turning the conical surface 49 in its engagement with the extension 48 of the pump rotor 24, the pump rotor 24 is by means of teeth or knurling provided on the engaging surface carried along and rotated so that any accumulation of limestone or the like will break off and that during the start of the pump the direction of rotation of the pump rotor 24 can be observed. The liquid which leaves the region of the pump rotor 24 in radial direction is also in this instance by ribs 28 deviated into the axial direction of the pump and is conveyed to the pressure conduit.

The chamber 29 of housing 1 which houses the rotor 22 is sealed relative to chamber 30 which receives the stator 11 with the coils 12 by means of a collimator or sleeve 31 which is coaxially arranged with regard to the pump axis. The collimator or sleeve 31 has a cylindrical extremely thin mantle 32 which surrounds the rotor 22 and the pump rotor 24 and may, for instance, engage the inner surface of the stator 11. The collimator or sleeve 31 comprises at a first end a first annular discshaped flange 33 and has its other end provided with a second mantle-shaped flange 34. The annular discshaped flange 33 which is formed by the radial inner range of a truncated cone-shaped end wall 35 of the collimator or sleeve 31 has its outer end face in engagement with the inner end face of the holding flange l3 and has its inner surface resting in centering manner against the outer circumference of the hollow shaft 15 and the plug section 16 (FIGS. l-4) or against a radial supporting surface of the holding flange 13 (FIGS. 5 and 6). Within the region of flange 33, the liquid-filled chamber 29 is relative to the air-filled chamber 30 sealed by at least one annular disc-shaped seal 36. According to the embodiment of FIGS. 1 and 2, the seal 36 engages that end face of the first flange 33 which faces away from the holding flange 13 and has an outer diameter which corresponds to that of the holding flange 13. The flange 33 and the seal 36 are clamped between the inner collar 19 of the hollow shaft 15 and the inner end face of the holding flange 13 so that an effective seal is obtained. The inner wall 35 and the clamped-in flange 33 of the collimator or sleeve 31 have with all embodiments a thickness which is considerably greater than the thickness of the mantle 32.

The second flange 34 of the collimator or sleeve 31 has an inner diameter which equals the inner diameter of the mantle 32 of the collimator 31 while the outer diameter of the flange 34 is greater than that of the mantle 32 so that also the flange 34 has a thickness which is' considerably greater than that of the mantle 32. That end face 37 of the flange 34 which faces away from the other end of the collimator or sleeve 31 rests against an annular disc-shaped seal 38 which is inserted in an annular shoulder on the inner side of the housing cover 2 and the outer diameter of which approximately equals the outer diameter of the flange 34. An annular extension 39 of the housing cover 2 extends over the outer circumference of the annular seal 38. The flange 34 engages the annular extension 39 in such a way that the flange is centered relative to the housing cover 2, if desired, through the intervention of sealing material. By connecting the housing cover 2 to the housing mantle 4, the annular seal 38 is pressed against the flange 34 so that also in this instance an effective seal is obtained.

An axial displacement of the hollow shaft 15 can with the pump according to the invention be prevented at any rate by mounting the hollow shaft 15 with press fit in the holding flange 13. To this end. during the assembly, the housing 1 is heated up in region of the holding flange 13, and the hollow shaft 15 is inserted so that the holding flange 13, after the latter has cooled off, will firmly embrace the hollow shaft 15. Frequently, pumps of this type are employed as circulating pumps for heated liquids, as, for instance, in heating installations so that the pump while in operation often absorbs considerable temperatures of the conveying medium. In view of the inherent heating up, it would be possible that the press fit will loosen and thus a harmful axial displacement of the hollow shaft and of the parts carried thereby would be possible relative to the housing 1. In order safely to avoid such accidents, also when the pump is heated up, the hollow shaft 15 is advantageously secured against .axial displacement by a positive connection with the holding flange 13. This positive connection is illustrated in the various embodiments in different ways.

According to the embodiment of FIGS. 1 and 2, a nut 41 forming a collar is screwed onto a part 40 of the outer threaded section 17 of the hollow shaft 15. This nut 41 rests against the outside of the pertaining housing end wall 3 and holding flange 13 respectively and can be tightened against the outer annular radial end face of the holding flange 13. By means of this nut, the hollow shaft 15 is clamped fast, and also the first flange 33 with the annular seal 36 is clamped between the inner collar 19 and the holding flange 13. The outer thread 42 of the outer threaded section 17 which thread 42 protrudes beyond the outer end face of nut 41 forms a connecting flange which is coaxial with the pump axis for connecting to the connecting flange a pipe line.

According to the pump of FIG. 3, while likewise employing an axial clamping element, a corresponding nut 41 is screwed onto the outer threaded section 17 of hollow shaft 15. This nut 41 engages the outside of the pertaining housing end wall 3 and can be tightened against the outer annular end face of the holding flange 13 so that it likewise forms an axially clamping outer collar. As a result thereof, the inner collar 19 of the hollow shaft 15 is pulled against its inner engaging surface on the holding flange 13 and thereby clamps fast the first inner flange 33 of the collimator. Between the collar 19 and the first flange 33 of the collimator 31 there is, according to FIG. 3, located the annular seal 36 which likewise, when tightening the nut 41, is pressed in and thus prevents liquid from escaping from chamber 29 into the air-filled chamber 30. That section of the holding flange 13 which protrudes from the end wall 3 has its outer side provided with an outer thread 42 which serves for connecting the connecting conduit by means of a box nut or the like. At the oppositely located housing side, the housing cover 2, in all embodiments, has a similarly designed connection 43 with an outer thread 44 for connecting a conduit thereto.

By clamping the hollow shaft 15 to the holding flange 13 by means of nut 41 and by simultaneously clamping the first flange 33 of the collimator or sleeve 31 in the embodiments of FIGS. 13, a stable and easily to be surveyed construction of the pump is obtained with a small axial construction length and with a simple possibility of assembling and disassembling the same. To this end, the hollow shaft 15 with annular seal 36 and assembled collimator or sleeve 31 is from the inner side of the housing inserted into the holding flange l3 whereupon the nut 41 is assembled and tightened so that the hollow shaft 15 will then be firmly connected, the rotor 22 being connected to the pump rotor 24. Finally, there remains merely the housing cover 2 to be mounted and to fasten the same by means of the clamping screws 7.

The provision of a separate nut as axial clamping element, however, requires certain additional structural elements which increase the costs when mass produc tion is involved. Experience has shown that such axial clamping element can be saved without sacriflzing the essential advantages of such a pump. Such construction has been realized by the designs of FIGS. 4-6. The pump according to the invention as illustrated in FIG. 4 has an outer collar 51 which forms one piece with the hollow shaft 15. The outer collar 51 is pressed against the outer end face of the holding flange 13 by means of a screw connection similar to a box nut. As a result thereof, the hollow shaft 15 is secured in its position relative to the housing of the pump without the necessity of a separate axial clamping element. At the oppositely located side of the holding flange 13, the hollow shaft 15 does no longer have a radially outwardly protruding collar corresponding to the collar 19. Therefore, the collimator is not clamped-in but merely engages the outer end side of the holding flange 13, while the sealing force is generated upon the annular seal 36 in the direction toward the holding flange 13 by the clamping screws 7. The clamping screws 7 also press the other flange 34 of the collimator 31 against the there located annular disc-shaped seal 38. Additionally, also the hollow shaft 15 is within the region of the seal 36 provided with a shoulder 52 located toward the rotor 22. The annular seal 36 extends into the shoulder 52 and is pressed-in in this area by the clamping force of the screw connection within the region of the collar 51. The bearing bushing 21, which with the pump according to the other embodiments is axially supported by the adjacent lateral surface of the collar 19, is in the present embodiment by a collar 53 of the hollow shaft 15 which is formed by a folded-over rim of a separate part of the hollow shaft 15, this part forming the bearing section 20. The bearing section 20 which receives the bearing bushing 21 of the rotor 22 may, for instance, be produced of a high greade stainless steel and may be connected by welding to the plug section 16 of the hollow shaft 15. The section 16 need not be produced of high grade and thereby expensive steel.

In order also in the absence of a clamping of the collar 51 to assure that the hollow shaft will be safely located in its respective position, the hollow shaft 15 is pressed into the holding flange 13. In view of the location of the fixed collar 51 on the outside of the housing, which location differs from that of the other embodiments, the hollow shaft 15 is, according to FIG. 4, inserted from the outside into the holding flange 13 of the heated up housing, whereupon from the other side the annular seal 36 as well as the collimator or sleeve 31 and the rotor 22 and pump rotor 24 are assembled, and finally the housing cover 2 is mounted. Thereupon the pump can, without risking a displacement of the parts, be shipped and installed, in which instance during the installation the collar 51 is first clamped fast whereby also during operation, when the pump is heated, the hollow shaft 15 will be secured in its position.

According to the embodiment of FIG. 5, an inner collar 19 is provided, similar to the pumps of FIGS. 1-3. As a result thereof, similar to the pumps of FIGS. 1-3, a seal by means of a sealing ring 36 can be effected between the collar 19 and the inner side of flange 33 of the collimator or sleeve 31. In addition thereto. similar to the embodiment of FIG. 4, also on the outside of the flange 33 toward the holding flange 13 an additional annular seal 36 is provided which increases the sealing effect. Instead of axially clamping the collar 19 against the holding flange 13 by means of a nut 41, in this instance, on the outside of hollow shaft 15 spreading elements 54 are provided which similar to a rivet connection extend behind a shoulder 55 on the inner surface of the holding flange 13. To this end, the spreading elements 54 are, after insertion of the hollow shaft 15, bent outwardly from the inside in their position of installation by means of a punch or the like. The simultaneous pressing-in of the hollow shaft 15 into the holding flange 13 will prevent a springing or deflection of the spreading elements 54. In order, during the deformation of the spreading elements 54, to avoid an undue deformation of the seals 36 and 36' and of the flange of the collimator or sleeve 31 located therebetween, the remaining stroke of the collar 19 is limited by an annular abutment 56 of the holding plate 13. As a result thereof, independently of the axial forces exerted upon the housing 1 and the hollow shaft 15 during the assembly, a predetermined pressing effect within the region of the flange 33 of the collimator 31 will be ob tained.

According to the embodiment of FIG. 6, the hollow shaft 15 will, even when a considerable heating up occurs, positively be secured in its position relative to the holding flange 13 in a manner similar to that of FIG. by spreading elements 57 which, however, axially protrude on the inner end face of the holding flange 13. The spreading elements 57 are formed by tongueshaped segments of a ring which extends the inner surface of the holding flange 13. The collar 19 of the hollow shaft has within its foot area a deflecting surface 58 which when inserting the hollow shaftlS into the plug shaft 13 engages the spreading elements 57 and bends the same inwardly. In this connection, the defleeting surface 58 forms a lateral confinement of a slot 59 in which the spreading elements 57, following the assembly, are located substantially free from play so that axial displacements of the hollow shaft 15 relative to the holding flange 13 will be avoided.

Thus, with the embodiment of FIG. 6, a positive connection between the hollow shaft 15 and the holding flange 13 is obtained in addition to the press fit without any separate working step because merely the pressingin of the hollow shaft 15 into the holding flange 13 is necessary up to the blocking of a further movement by the spreading elements 57 in slot 59, and a positive connection is established without any additional means or operations.

With the illustrated embodiments of a pump according to the invention, that part of the holding flange 13 which extends beyond the end face 3, and with the embodiment of FIG. 1 the outer part of the hollow shaft 15, is designed as suction connection, and the connection 53 is designed as pressure connection. The pump rotor 24 is by a corresponding shape of its blades 26 so designed that in both directions of rotation it will feed toward the pressure connection 43. However, a change in the pump characteristic can easily be obtained by exchanging the blades 26 or the pump rotor 24, if desired, together with the rotor 22. The inner diameter of the connection 43 substantially equals the inner diameter of the ribs 28 merging therewith and pertaining to the housing cover 2 and is substantially equal to the inner diameter of the hollow shaft 15 which, when the hollow shaft 15 is made as one piece (FIGS. 1-4 and 6), is constant over the entire length of shaft 15.

, The housing 1 may be produced of die-cast metal or gray cast iron, expediently of steel, and in particular that part which forms the bearing section 20 may be made of stainless steel, such as chromium steel, or the like. The pump rotor 24 may consist of synthetic material. The outside of the housing mentle 4 is provided with a terminal box 45 or a cable outlet for the electric connection of the pump.

The inner annular collar 19 of the hollow shaft 15 may be provided with a radial bore 46 (FIG. 1) which connects the interior of the hollow shaft 15 with the inner chamber of the collimator 31 on that side of the rotor 22 which faces toward the suction side of the rotor 22 so that on this side of rotor 22 a pressure drop occurs, and the rotor 22 will not press at too high a pressure in the direction toward the counter surface 27.

The pump according to the present invention, which is also suited for delivering liquids at high temperatures, in addition to having small dimensions, is reversible and furthermore the centric construction has the advantage that it is self-ventilating and that the danger of soiling of the bearings is very small, and that it has excellent lubricating properties as well as a favorable withdrawal of heat from the motor. The simple and easily to be surveyed construction is suited for the socalled building block principle so that a unitary construction is obtained for a number of rated outputs and pole numbers.

It is, of course, to be understood that the present invention is, by no means, limited to the specific showing in the drawings but also comprises any modifications within the scope of the appended claims.

What is claimed is:

1. In combination: a pump impeller and a drive motor therefor in coaxial adjacent relation, said motor comprising a stator and a tubular rotor, said impeller being drivingly connected to one end of said rotor, a common housing for said pump impeller and stator, a collimator sleeve extending axially along the inside of the stator and forming a fluid seal in the housing isolating the rotor and pump impeller from the stator, a fluid inlet in said housing leading into one end of said sleeve and a fluid outlet in said housing leading from the other end of said sleeve, a hollow shaft comprising a readily separable knock-out spindle interchangeably carried by said housing in centered accurate alignment therewith and secured against axial displacement extending axially into and rotatably supporting said rotor for quiet operation and being less susceptible to wear, said hollow shaft communicating with said fluid inlet and the discharge side of said pump impeller communicating with said fluid outlet, said housing having a generally radial shoulder thereon facing said rotor, and a substantially radial flange extending transversely of said knock-out spindle and located on one end of said sleeve only sealingly clamped engaging in a centered position against said shoulder.

2. A combination according to claim 1 in which said housing has a separable first end cover at the outlet end and having said fluid outlet herein, said housing having a cylindrical central portion surrounding said stator and a second end cover integral therewith at the inlet end of the housing and having said fluid inlet therein, a tubular portion formed on said second end cover in which said hollow shaft is mounted, said tubular portion having said radial shoulder thereon, and a collar on said hollow shaft engaging said radial flange of said sleeve element on the side opposite said radial shoul der.

3. A combination according to claim 2 in which said hollow shaft is press filtered into said tubular portion.

4. A combination according to claim 2 in which said hollow shaft protrudes outwardly from said second end cover, and a fastening means mounted on the hollow shaft and engaging the outside of said second end cover, the protruding end of said hollow shaft forming said fluid inlet.

5. A combination according to claim 4 in which said fastening means is a nut threaded on the protruding end of said hollow shaft.

6. A combination according to claim 5 in which the hollow shaft protrudes beyond said nut toward the outside of the housing and is adapted for the connection thereto of an inlet conduit.

7. A combination according to claim 2 in which said tubular portion has a shoulder therein facing away from said rotor, and said hollow shaft has the axially outer end in the axial region of said shoulder and formed radially outwardly into clamping engagement with said shoulder.

8. A combination according to claim 2 in which said hollow shaft has an annular recess formed therein at the junction of said collar with said hollow shaft, said tubular portion having means protruding axially from the inner side of said radial shoulder and adapted to enter said recess and to be deformed therein to clamp said hollow shaft to said tubular portion.

9. A combination according to claim 2 in which said sleeve at the end opposite said radial flange has an axially facing annular surface, said first end cover having an axial surface engaging the axial surface on said sleeve and a projection on said first end cover engaging one radial side of the sleeve adjacent said annular surface.

10. A combination according to claim 9 which includes seal elements interposed between said end covers and the opposite ends of said sleeve and in pressure engagement with said radial flange and with said annular surface of said sleeve.

11. A combination according to claim 10 in which said seal elements are heat resistant.

12. A combination according to claim 1 which includes a bearing bushing in the rotor engaging said hollow shaft, and a collar on said hollor shaft engaging the axial end of said bushing.

13. A combination according to claim 1 in which said hollow shaft includes a stainless steel portion extending into said rotor and a portion welded to said stainless steel portion and engaged by said housing.

14. A combination according to claim 1 in which said pump impeller is fixed to the end of said rotor nearest said first end cover, said impeller discharging peripher ally and having an imperforate wall on the side facing said first end cover, the periphery of said impeller being spaced radially from said sleeve, and axial ribs on the impeller side of said first end cover extending to adjacent said imperforate wall.

15. A combination according to claim 1 in which said hollow shaft includes passage means extending radially through one side thereof near the end of said rotor nearest said fluid inlet.

16. A combination according to claim 2 in which the free axial length of said sleeve is greater than the axial distance between said radial shoulder and said axial surface on said first end cover whereby when the said first end cover is mounted on said housing said sleeve will be in a state of axial compression.

17. A combination according to claim 1 which includes means mounted in said housing and radially adjustable therein into locking engagement with said pump impeller. 

1. In combination: a pump impeller and a drive motor therefor in coaxial adjacent relation, said motor comprising a stator and a tubular rotor, said impeller being drivingly connected to one end of said rotor, a common housing for said pump impeller and stator, a collimator sleeve extending axially along the inside of the stator and forming a fluid seal in the housing isolating the rotor and pump impeller from the stator, a fluid inlet in said housing leading into one end of said sleeve and a fluid outlet in said housing leading from the other end of said sleeve, a hollow shaft comprising a readily separable knock-out spindle interchangeably carried by said housing in centered accurate alignment therewith and secured against axial displacement extending axially into and rotatably supporting said rotor for quiet operation and being less susceptible to wear, said hollow shaft communicating with said fluid inlet and the discharge side of said pump impeller communicating with said fluid outlet, said housing having a generally radial shoulder thereon facing said rotor, and a substantially radial flange extending transversely of said knock-out spindle and located on one end of said sleeve only sealingly clamped engaging in a centered position against said shoulder.
 1. In combination: a pump impeller and a drive motor therefor in coaxial adjacent relation, said motor comprising a stator and a tubular rotor, said impeller being drivingly connected to one end of said rotor, a common housing for said pump impeller and stator, a collimator sleeve extending axially along the inside of the stator and forming a fluid seal in the housing isolating the rotor and pump impeller from the stator, a fluid inlet in said housing leading into one end of said sleeve and a fluid outlet in said housing leading from the other end of said sleeve, a hollow shaft comprising a readily separable knock-out spindle interchangeably carried by said housing in centered accurate alignment therewith and secured against axial displacement extending axially into and rotatably supporting said rotor for quiet operation and being less susceptible to wear, said hollow shaft communicating with said fluid inlet and the discharge side of said pump impeller communicating with said fluid outlet, said housing having a generally radial shoulder thereon facing said rotor, and a substantially radial flange extending transversely of said knock-out spindle and located on one end of said sleeve only sealingly clamped engaging in a centered position against said shoulder.
 2. A combination according to claim 1 in which said housing has a separable first end cover at the outlet end and having said fluid outlet therein, said housing having a cylindrical central portion surrounding said stator and a second end cover integral therewith at the inlet end of the housing and having said fluid inlet therein, a tubular portion formed on said second end cover in which said hollow shaft is mounted, said tubular portion having said radial shoulder thereon, and a collar on said hollow shaft engaging said radial flange of said sleeve element on the side opposite said radial shoulder.
 3. A combination according to claim 2 in which said hollow shaft is press fitted into said tubular portion.
 4. A combination according to claim 2 in which said hollow shaft protrudes outwardly from said second end cover, and a fastening means mounted on the hollow shaft and engaging the outside of said second end cover, the protruding end of said hollow shaft forming said fluid inlet.
 5. A combination according to claim 4 in which said fastening means is a nut threaded on the protruding end of said hollow shaft.
 6. A combination according to claim 5 in which the hollow shaft protrudes beyond said nut toward the outside of the housing and is adapted for the connection thereto of an inlet conduit.
 7. A combination according to claim 2 in which said tubular portion has a shoulder therein facing away from said rotor, and said hollow shaft has the axially outer end in the axial region of said shoulder and formed radially outwardly into clamping engagement with said shoulder.
 8. A combination according to claim 2 in which said hollow shaft has an annular recess formed therein at the juncture of said collar with said hollow shaft, said tubular portion having means protruding axially from the inner side of said radial shoulder and adapted to enter said recess and to be deformed therein to clamp said hollow shaft to said tubular portion.
 9. A combination according to claim 2 in which said sleeve at the end opposite said radial flange has an axially facing annular surface, said first end cover having an axial surface engaging the axial surface on said sleeve and a projection on said first end cover engaging one radial side of the sleeve adjacent said annular surface.
 10. A combination according to claim 9 which includes seal elements interposed between said end covers and the opposite ends of said sleeve and in pressure engagement with said radial flange and with said annular surface of said sleeve.
 11. A combination according to claim 10 in which said seal elements are heat resistant.
 12. A combination according to claim 1 which includes a bearing bushing in the rotor engaging said hollow shaft, and a collar on said hollow shaft engaging the axial end of said bushing.
 13. A combination according to claim 1 in which said hollow shaft includes a stainless steEl portion extending into said rotor and a portion welded to said stainless steel portion and engaged by said housing.
 14. A combination according to claim 1 in which said pump impeller is fixed to the end of said rotor nearest said first end cover, said impeller discharging peripherally and having an imperforate wall on the side facing said first end cover, the periphery of said impeller being spaced radially from said sleeve, and axial ribs on the impeller side of said first end cover extending to adjacent said imperforate wall.
 15. A combination according to claim 1 in which said hollow shaft includes passage means extending radially through one side thereof near the end of said rotor nearest said fluid inlet.
 16. A combination according to claim 2 in which the free axial length of said sleeve is greater than the axial distance between said radial shoulder and said axial surface on said first end cover whereby when the said first end cover is mounted on said housing said sleeve will be in a state of axial compression. 